So you want to demolish all the car parks that already exist? All of them, tomorrow? Don't you think it will take some time before the builders can come and replace the last car park in your country with whatever it's going to be replaced with? During that time, would it not be better to put solar panels on it? (And then remove them before it gets demolished and put them somewhere else)
I am not American, I just think it's a stupid criticism of such a plan that we "shouldn't have cars and therefore shouldn't have car parks" because the fact is that we already do have them so we may as well use them as best we can.
In any case I don't agree on a total ban on cars entering city centres, at least not in the foreseeable future. The most bike-friendly cities I have lived in and visited have also had many cars. I suspect there is a place for personal cars, deprioritised compared to buses and bikes, in most cities for many years to come. During that time there will need to be car parks. Those car parks should have solar panels on, along with pretty much all other buildings.